Since March, we've known that nearly all COVID deaths involve comorbidities, like diabetes, obesity, or heart disease (94% in the US, per CDC).

Is this unusual? Not really. In 2018, 66% of deaths in the top 15 underlying causes had multiple contributing causes. 1/

85% of influenza & pneumonia deaths listed multiple causes of death (MCD). Even in cancer and accident deaths, a majority listed other contributing factors. Of the top 15 underlying causes of death, only suicides predominately list a single cause. 2/

So it's not surprising -- even in the abstract -- that 94% of COVID deaths list other causes. Death certificates encourage listing contributing factors because dead people rarely had just one problem. 3/

When you also consider that 45% of all American adults (and 81% of those 80+) have at least one of six common COVID comorbidities, it would be surprising if they didn't. 4/ https://www.medrxiv.org/content/10.1101/2020.03.30.20043919v1

There is a non-trivial question here about how many deaths should have covid as a contributing factor (MCD) vs. the underlying cause of death (UCD). CDC says that covid is listed as the UCD 95% of the time vs. 5% when it is a MCD. 5/ https://www.cdc.gov/nchs/nvss/vsrr/covid19/excess_deaths.htm

This is as opposed to flu and pneumonia, which are the UCD (what we call "flu deaths") in just 31% of deaths that involve flu -- and only very rarely (7%) the solitary listed cause (again, typical for any cause of death). 6/

Excess deaths outnumber confirmed deaths, which implies we are missing some covid-caused deaths. In these cases, covid may be more likely to be a contributing cause and therefore to be missed than cases where it was obviously the primary cause. 7/

Source is CDC WONDER. Select a UCD-113 cause (section 6), then search within it for MCDs (section 7). Use "Select Records with any of these items:" and add all other causes of death, excluding the UCD. https://wonder.cdc.gov/mcd-icd10.html 

NB: accidents and suicides also have separate sequelae and "other consequences" MCD codes that should be excluded (S00-T98, Y85-Y89, etc.).